Computer graphics systems are typically used to examine and perform operations on large, detailed, digital images. Examples of such tasks include an artist editing a high-resolution image for print publication, an image analyst examining an aerial photograph, and a silicon chip designer examining chip layouts. Often, users of such graphics systems may desire to zoom-in to specific regions of a particular image in order to recognize detail. When zoomed-in to a specific region of interest, the entire image may not fit on the display screen of the system and hence a large portion of the image may no longer be visible to the user. If the user, still zoomed-in, wants to navigate to a different region of the image, the user typically first zoom-outs and then zooms back in, or pans repeatedly until the new region of interest is located. Both of these operations are slow and time consuming. Thus, conventional methods of navigating large images such as panning and zooming may be inefficient. This is an example of what has been referred to as the “screen real estate problem”.
U.S. Pat. No. 6,271,854 to Light discloses a method for navigating in three-dimensional graphic scenes. In Light, a user may zoom-in to an object in a scene by clicking on the object. To zoom-out to the original scene, an “opportunistic” control icon is provided. By clicking on this control, the original scene is redisplayed. The user may then select another object in the original scene to zoom-in on. However, the screen real estate problem remains evident in Light. When viewing an object which has been zoomed-in, the relationship between that object and other objects in the original scene may be lost to the user.